Practical interventions to promote circadian adaptation to permanent night shift work: study 4

Details

• Personal Author:
  Eastman CI ; Fogg LF ; Smith MR
• Description:
  Scheduled bright light and darkness can phase shift the circadian clocks of night workers for complete adaptation to a night work, day sleep schedule, but few night workers would want this because it would leave them out of phase with the diurnal world on days off. This is the final study in a series designed to produce a compromise circadian phase position for permanent night shift work in which the sleepiest circadian time is delayed out of the night work period and into the first half of the day sleep episode. The target compromise phase position was a dim light melatonin onset (DLMO) of 3:00, which puts the sleepiest circadian time at approximately 10:00. This was predicted to improve night shift alertness and performance while permitting sufficient daytime sleep after work as well as late-night sleep on days off. In a between-subjects design, 19 healthy subjects underwent 3 simulated night shifts (23:00-7:00), 2 days off, 4 more night shifts, and 2 more days off. Subjects "worked" in the lab and slept at home. Experimental subjects received four 15-min bright light pulses during each night shift, wore dark sunglasses when outside, slept in dark bedrooms at scheduled times, and received outdoor afternoon light exposure ("light brake") to keep their rhythms from delaying too far. Control subjects remained in normal room light during night shifts, wore lighter sunglasses, and had unrestricted sleep and outdoor light exposure. The final DLMO of the experimental group was 3:22 +/- 2.0 h, close to the target of 3:00, and later than the control group at 23:24 +/- 3.8 h. Experimental subjects slept for nearly all the permitted time in bed. Some control subjects who slept late on weekends also reached the compromise phase position and obtained more daytime sleep. Subjects who phase delayed (whether in the experimental or control group) close to the target phase performed better during night shifts. A compromise circadian phase position improved performance during night shifts, allowed sufficient sleep during the daytime after night shifts and during the late nighttime on days off, and can be produced by inexpensive and feasible interventions. [Description provided by NIOSH]
• Subjects:
  Circadian Rhythm Men Occupational Health Safety Shift Work Schedule Sleep Initiation And Maintenance Disorders Women Workload
• Keywords:
  Author Keywords: Human Bright Light Circadian-rhythms Circadian Rhythms Fatique Humans Melatonin Performance Shift-work Shift-workers Shift Work Sleep Sleep-disorders Work-capability Work-capacity Workers

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• ISSN:
  0748-7304
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  Illinois ; OSHA Region 5
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  161-172
• Volume:
  24
• Issue:
  2
• NIOSHTIC Number:
  nn:20045632
• Citation:
  J Biol Rhythms 2009 Apr; 24(2):161-172
• Contact Point Address:
  Charmane I. Eastman, PhD, Biological Rhythms Research Laboratory, 1645 W. Jackson Blvd., Suite 425, Chicago, IL 60612
• Email:
  ceastman@rush.edu
• Federal Fiscal Year:
  2009
• Performing Organization:
  Rush University Medical Center, Chicago, Illinois
• Peer Reviewed:
  True
• Start Date:
  19990930
• Source Full Name:
  Journal of Biological Rhythms
• End Date:
  20090430
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:6bdbc9de15777b73076f5b24f0b54a7e59855d13c38c5220342a808088158e93fd23ad1ccc0d697fb7775ac2d5e363db916ce6c5e9ef2c32c5d090b5c5509f52
• Download URL:
  https://stacks.cdc.gov/view/cdc/200982/cdc_200982_DS1.pdf
• File Type:
  [PDF - 353.46 KB ]